United's 2-0 victory over the Chicago Fire in Wednesday's semifinal accomplished that despite the worst record in Major League Soccer.

D.C. scored its fourth win of the tournament. It has three victories in MLS competition this season, along with 15 losses and four ties, but it's unbeaten in the U.S. Soccer Federation's all-comers tournament. United will visit Real Salt Lake in the final on Oct. 1.

The outcome made up for a 4-1 loss to Chicago in MLS play on the same field on July 20. The Fire outclassed D.C. from start to finish.

"It was a spanking," said United forward Dwayne De Rosario. "It was tough even to watch."

De Rosario was absent for that game, recovering from an adductor strain. Fully healed, he came back to action last week, and scored the first of United's two goals Wednesday.

"I wanted to set the tone," De Rosario said.

He did, pouncing on a ball goalkeeper Sean Johnson bobbled, taking two steps to the left, and booting it home from 4 yards in the 44th minute.

Then came Nick DeLeon, United's other threat, and also injured until recently. He scored in the 48th minute, ripping a low 13-yard shot to Johnson's left after slaloming through a pair of defenders.

D.C.'s Joe Willis made six saves.

"The last two games, we've looked like a team," United coach Ben Olsen said. "We've been able to understand this is extremely important. Our best shot at a trophy is in the Open Cup."

The Fire pushed hard in the last 20 minutes, but failed to score.

Willis made a difficult save on Alex in the 76th minute, then watched Austin Berry's deflected shot carom off the goal post a minute later. In the first 27 minutes, Willis solved Chris Rolfe and Alex, after which United's midfield began to take command.

But the goals were still stunners.

"They got a little bit of fortune tonight," Fire midfielder Jeff Larentowicz said. "They score (the first goal) on a mistake, and after their second, I don't know how we don't score."

For United, playing for a championship in a dismal season is heartening.

"It's coming together a little late, but it feels good," DeLeon said.

"Three wins (in MLS), but we're playing for a championship nonetheless.

"You get rewarded sometimes."

Neither Chicago nor D.C. United is above .500 in MLS competition, but advanced to the U.S. Open Cup semifinals by beating a combination of MLS and lower-level professional squads. United had beaten Richmond of the USL Pro circuit, and MLS foes Philadelphia and New England, to earn the right to play Chicago.